I used a simple usb cable to a usb/ac adapter last night and it charged fine.

I was reading in bed and battery died, I didn't feel like coming out to living room to plug into my computer to charge, but wanted it charged to read today, so I just plugged it into my usb cable i had plugged in there to charge my phone.

All you need is the ac adaptor then you can just plug the usb cable into it.